Various software data, such as audio data such as music, image data such as movies, game programs, and various kinds of application programs (hereinafter, these will be referred to as “content”), can be stored as digital data on a recording medium, for example, a Blu-ray disc (trademark) for which a blue laser is used, a DVD (Digital Versatile Disc), an MD (Mini Disc), and a CD (Compact Disc). In particular, a Blu-ray disc (trademark) for which a blue laser is used is a disc capable of being used for high-density recording and is capable of having a large amount of video content or the like recorded thereon as high-quality data.
Digital content is stored on these various information recording media and is provided to a user. The user uses a reproduction device, such as a PC (Personal Computer) or a disc player, to reproduce and use the content.
In general, sales rights or the like of most content, such as music data and image data, are held by the creator thereof or the seller thereof. Therefore, when distributing these pieces of content, it is common practice that a fixed use limitation is imposed, that is, use of content is permitted only for an authorized user so that copying without permission or the like will not be performed.
In a digital recording apparatus and a recording medium, for example, images and audio can be repeatedly recorded and reproduced without degrading them. Therefore, problems such as the following have occurred: the distribution of illegally copied content via the Internet, the distribution of so-called pirated discs produced using CD-Rs and the like, onto which content has been recorded, and wide use of copied content stored in a hard disk of a PC or the like.
It is possible for a DVD or a large-capacity recording medium, such as a recording medium using a blue laser whose development has progressed in recent years, to have a large amount of data recorded thereon for one to several movies as digital information on one medium. When it became possible to record video information and the like as digital information in the manner described above, it became increasingly important to prevent illegal copying and protect the rights of a copyright holder. In recent years, in order to prevent such illegal copying of digital data, various technologies for preventing illegal copying to digital recording apparatuses and recording media have been implemented.
As one method for protecting a copyright holder by preventing illegal copying of content, a content encryption process is known. However, even if content is encrypted, if the leakage of an encryption key occurs, a problem of illegally decrypted content being leaked can occur. In the related art, one configuration that solves such a problem as disclosed in Patent Document 1 is known. Patent Document 1 discloses a configuration in which illegal reproduction of content is prevented in such a manner that some of content is recorded by being replaced with dummy data.
When performing a process for reproducing content in which content has been replaced with dummy data, a process for replacing the dummy data with normal content data becomes necessary. This data conversion process needs to be performed without normal content being leaked to the outside. Furthermore, it is preferable that processing information, such as the position at which the dummy data is arranged and the conversion method, be prevented from being leaked.
As described above, when reproducing content, it is necessary to perform a content decryption process and a data conversion process. Furthermore, there is a case in which a security check, such as an authenticity confirmation process of confirming whether an information processing apparatus or a reproduction (player) program that is going to use content is a device or a program that has received a valid license, is performed. Such data processing is performed by executing content code recorded as a content-use control program together with content on an information recording medium. An example of a content-use process using content code is described in, for example, Patent Document 1.
Content code is set as a file independent of content and is recorded on an information recording medium. Therefore, a process for moving only content code to another information recording medium and a process for copying become possible. If leakage of content code occurs and the content code is illegally distributed and used, there is a possibility that many pieces of content can be illegally distributed and used, and great damages occur.
It is considered that, as apparatuses and applications for performing content reproduction, different apparatuses and applications of various makers are used. When a security check and a data conversion process using content code are to be performed, the following setting is preferably performed that appropriate content code compliant with players, such as different apparatuses and applications of various makers, is selected, a security check in accordance with each sequence is performed, and a unique data conversion process compliant with players is performed. In particular, in data conversion, there is a case in which player identification information is embedded into content. Thus, when correct content code compliant with a player is not selected, there is a problem in that correct player identification information is not embedded.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002-311998